模板。
——代码
1 #include <cstdio> 2 #include <iostream> 3 #define N 300001 4 #define get(x) (son[f[x]][1] == (x)) 5 #define swap(x, y) ((x) ^= (y) ^= (x) ^= (y)) 6 #define isroot(x) (son[f[x]][0] ^ (x) && son[f[x]][1] ^ (x)) 7 8 int n, m; 9 int a[N], sum[N], son[N][2], rev[N], f[N], s[N]; 10 11 inline int read() 12 { 13 int x = 0, f = 1; 14 char ch = getchar(); 15 for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1; 16 for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0'; 17 return x * f; 18 } 19 20 inline void update(int x) 21 { 22 if(x) 23 { 24 sum[x] = a[x]; 25 if(son[x][0]) sum[x] += sum[son[x][0]]; 26 if(son[x][1]) sum[x] += sum[son[x][1]]; 27 } 28 } 29 30 inline void pushdown(int x) 31 { 32 if(x && rev[x]) 33 { 34 swap(son[x][0], son[x][1]); 35 if(son[x][0]) rev[son[x][0]] ^= 1; 36 if(son[x][1]) rev[son[x][1]] ^= 1; 37 rev[x] = 0; 38 } 39 } 40 41 inline void rotate(int x) 42 { 43 int old = f[x], oldf = f[old], wh = get(x); 44 45 if(!isroot(old)) 46 son[oldf][get(old)] = x; 47 f[x] = oldf; 48 49 son[old][wh] = son[x][wh ^ 1]; 50 f[son[old][wh]] = old; 51 52 son[x][wh ^ 1] = old; 53 f[old] = x; 54 55 update(old); 56 update(x); 57 } 58 59 inline void splay(int x) 60 { 61 int i, fa, t = 0; 62 s[++t] = x; 63 for(i = x; !isroot(i); i = f[i]) s[++t] = f[i]; 64 for(i = t; i >= 1; i--) pushdown(s[i]); 65 for(; !isroot(x); rotate(x)) 66 if(!isroot(fa = f[x])) 67 rotate(get(x) ^ get(fa) ? x : fa); 68 } 69 70 inline void access(int x) 71 { 72 for(int t = 0; x; t = x, x = f[x]) splay(x), son[x][1] = t, update(x); 73 } 74 75 inline void reverse(int x) 76 { 77 access(x); 78 splay(x); 79 rev[x] ^= 1; 80 } 81 82 inline int query(int x, int y) 83 { 84 reverse(x); 85 access(y); 86 splay(y); 87 return sum[y]; 88 } 89 90 inline int find(int x) 91 { 92 access(x); 93 splay(x); 94 while(son[x][0]) x = son[x][0]; 95 return x; 96 } 97 98 inline void link(int x, int y) 99 { 100 reverse(x); 101 f[x] = y; 102 access(x); 103 } 104 105 inline void change(int x, int y) 106 { 107 access(x); 108 splay(x); 109 a[x] = y; 110 update(x); 111 } 112 113 int main() 114 { 115 int i, x, y; 116 char s[10]; 117 n = read(); 118 for(i = 1; i <= n; i++) a[i] = read(); 119 m = read(); 120 for(i = 1; i <= m; i++) 121 { 122 scanf("%s", s); 123 x = read(); 124 y = read(); 125 if(s[0] == 'b') 126 { 127 if(find(x) ^ find(y)) link(x, y), puts("yes"); 128 else puts("no"); 129 } 130 if(s[0] == 'p') change(x, y); 131 if(s[0] == 'e') 132 { 133 if(find(x) ^ find(y)) puts("impossible"); 134 else printf("%d ", query(x, y)); 135 } 136 } 137 return 0; 138 }